Overview

The 2014 Nobel Prize in Physics honors scientists Isamu Akasaki, Hiroshi Amano, and Shuji Nakamura for the invention of the blue light-emitting diode (LED), a breakthrough in technology that has revolutionized electronic displays and residential and commercial lighting.

LEDs are made from layers of semiconductors, materials that act like a cross between a conductor and an insulator, and whose electrical properties can be controlled with the addition of impurities called dopants. Light is emitted from LEDs when a current is applied, driving excess electrons from one layer (the n-layer) to recombine with positive “holes” from another layer (the p-layer). The wavelength of this light depends on the material properties of the semiconductors.

Scientists’ understanding of the fundamental physics of semiconductors progressed rapidly in the 1940s, which led to numerous applications including LEDs—the first of which were created in the 1950s, ‘60s, and ‘70s, but emitted visible light only from the red to green part of the spectrum. Blue and ultraviolet LEDs remained stubbornly difficult to manufacture for more than three decades.

Akasaki, Amano, and Nakamura chose gallium nitride as the main component for blue light LEDs, even though the material was notoriously difficult to work with. Researchers had struggled for years to grow high-quality gallium nitride crystals and repeatedly failed to create a p-type layer.

Yet through thousands of experiments the three 2014 Nobel laureates persisted. Working together, Akasaki and Amano succeeded in growing high-quality gallium nitride crystal on top of an aluminum nitride layer on a sapphire substrate. Nakamura developed an alternate method, growing a thin layer of gallium nitride at a low temperature before growing subsequent layers at a higher temperature. The three researchers also developed novel ways to create p-layers.

The introduction of blue LEDs in the 1990s provided the missing piece for the widespread adoption of the new lighting technology. Blue LEDs have been used to create white light by combining them with other materials known as phosphors—or by mixing their light with the light from red and green LEDs.

This type of lighting now illuminates homes, offices and streets. It enables the backlight displays on cell phones, tablets, computers and TVs. And it does so greenly—LEDs are very long lasting and highly energy efficient, saving precious resources as the human population and its demands for artificial light continue to grow.

Quotes from AIP Leadership and Journal Editors

Statement from AIP Executive Director and CEO H. Frederick Dylla

"The blue LED is a fundamental invention that is rapidly changing the way we bring light to every corner of the home, the street and the workplace—a practical invention that comes from a fundamental understanding of physics in the solid state," said H. Frederick Dylla, the executive director and CEO of the American Institute of Physics.

"With the International Year of Light in 2015, the world will be celebrating LEDs and their efficient, commercial applications for general lighting, high-tech research and life-saving medicines," he added.

Statement from AIP Publishing CEO John Haynes

"The rich history of LEDs has been chronicled in AIP Publishing journals since the discovery of red LEDs by Nick Holonyak appeared in Applied Physics Letters in 1962," said John Haynes, CEO of AIP Publishing LLC. "Today we celebrate the Nobel Prize committee's recognition of blue LEDs by making a selection of articles related to those discoveries freely available to the public."

Statement from Reuben T. Collins, Editor-in-Chief of Applied Physics Letters and Professor of Physics, Colorado School of Mines

"This award recognizes an accomplishment that began in a lab as a fundamental advance in applied science and is now poised to touch every life on the globe. The invention of blue light emitting diodes is a model for the way in which science and technology can improve our world. In addition to the impact blue and UV LEDs are having on lighting technology, their high energy efficiency has led to use in televisions and computer displays. They are the basis for a revolution in optical storage with blue wavelengths allowing much greater information density in blu-ray discs than previously possible. The family of new materials born from the initial discovery are now making their way into the highest efficiency solar cells. We can only imagine how this innovation will continue to impact and benefit mankind in the future."

"The development of a practicable way to produce GaN was a true breakthrough in Applied Physics and has finally found well deserved recognition. The wide implications to energy efficiency and quality of life become more obvious by the day."

From Physics Today

AAPT resource for teaching about the science behind the prize

In celebration of the 2014 Nobel Prize in Physics, AAPT has developed a new resource to help its members and the physics community teach about the science behind the Nobel Prize. The webpage, Diodes: Articles for Physics Educators, contains articles from AAPT publications The Physics Teacher and the American Journal of Physics.

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